Astronomy Picture Of the Day (APOD)

We live in a forest.
Strewn throughout the universe are "trees" of hydrogen gas that absorb light from distant objects.
These gas clouds leave numerous
absorption lines in a distant
quasar's spectra, together called the
Lyman-alpha forest.

The first, and so far only,
lunar
astronomical observatory was deployed by the
Apollo 16 crew in 1972.
The Far
Ultraviolet Camera / Spectrograph used a 3-inch diameter
Schmidt telescope to photograph the
Earth,
nebulae,
star clusters,
and the Large Magellanic Cloud.

Amazingly detailed,
this
false-color x-ray image is centered on the galaxy Cygnus A.
Recorded by the orbiting
Chandra Observatory, Cygnus A is
seen here as a
spectacular high energy x-ray source.
But it is actually more
famous at the low energy end of
the electromagnetic spectrum as one of
the brightest celestial radio sources.

With brilliant
Venus above the western horizon at sunset and
Jupiter and
Saturn
high in the east by early evening,
November's night sky is filled with bright planets.
October's sky featured bright planets as well and, triggered
by the active Sun, some lovely
auroral displays.

Because the Gum Nebula is the closest
supernova remnant,
it is actually hard to see.
Spanning 40
degrees across the sky, the nebula is so
large and faint
it is easily lost in the
din of a bright and complex background.

If sometimes it appears that the entire
Milky Way Galaxy is raining down on your head,
do not despair.
It happens twice a day.
As the
Sun rises in the East,
wonders of the night sky become less bright than the
sunlight scattered by our own
Earth's atmosphere, and so fade from view.

What happens when a
comet encounters a planet?
If the planet has a rocky surface, a
huge impact feature will form.
A giant planet like Jupiter, however, is mostly
gas.
When
Comet Shoemaker-Levy 9 struck Jupiter in 1994,
each piece was
swallowed
into the vast
Jovian atmosphere.

Is it art?
In November of 1969,
Apollo 12 astronaut-photographer
Charles "Pete" Conrad recorded
this masterpiece while documenting colleague Alan Bean's
lunar soil collection activities on
the Oceanus Procellarum.
The image is dramatic and stark.
Bean is faceless.

Which planet has the most moons?
For now, it's Saturn.
Four newly discovered
satellites bring the ringed planet's
total to twenty-two, just edging out
Uranus' twenty-one for
the most
known moons in the solar system.
Of course, the newfound
Saturnian
satellites are not
large and
photogenic.